mej
Senior Member
- Joined
- Apr 17, 2011
- Messages
- 430
- Reaction score
- 3
- Location
- IoM and Languedoc
- Your Mercedes
- S124 1994 OM606, ditto OM605, ditto M111, W126, S211, W169
Having just stripped down the duo valve and back flushed the heater matrix (from duo valve (stbd) side to the inlet (port) side I still have no cabin heat (E300DT S124.191). There is 12v to the duo valve plug on cold, and 0v on max hot, as there should be; the duo valves can be heard and felt to jump when 12v is applied to the terminals from an external source. My arms aren't long enough to check this at the moment the heater wheels are set to hot or cold. When intermediate temperatures are set, there is no 'pulsing' of the valves. As for the matrix, I obtained 5.5l per minute on the back flush with a tiny head of water (about 6' max so little pressure). This suggests to me the matrix is OK. I have the WIS sheets on checking the system, and the last ditch stand is to replace the matrix, but I can't think this is necessary. Has anyone been here before?